I have just finished reading Cinema Alchemist, Roger Christian's book about how he detailed sets and created props on Star Wars and A L I E N...
He mentions these lamps... as lamps he found in a shop. They were denominated as "red heads", so I suppose they were already that color.
It's obvious though that the handle was added later...
Contec's theory is very tempting, it brings fresh air to the research on that prop...